Percussion fuze for a missile and procedure for the assembly of same



March 17, 1970 HAGER ETAL 3,500,748

PERCUSSION FUZE FOR A MISSILE AND PROCEDURE FOR THE ASSEMBLY OF SAME Filed Nov. 25, 1968 2 Sheets-Sheet 1 AUGUST HAGER &

LOUIS BIAGGI, Inventors Attorneys March 17, 1970 A. HAGER ETAL 3,500,748

PERCUSSION FUZE FOR A MISSILE AND PROCEDURE FOR THE ASSEMBLY OF SAME Filed NOV. 25, 1968 2 Sheets-Sheet 2 I L I 359 1F 44 45 37 m L 35 I7 4? 3a 31 37 48 20 r 29 w- AUGUST HAGER &

LOUIS BIAGGI,

Inventors Attorn eys 11.5. Cl. 102-79 2 Claims ABSTRACT OF THE DISCLOSURE Percussion fuze for a missile having a casing and a fuze cap having a bore. A firing pin with an extension firing pin having a frontal face and a lateral face projecting movably into the bore. The diameter of the lateral face is smaller than the diameter of the bore. An annular packing is located with one side on the frontal and lateral faces of the extension firing pin and with the other side abutting the wall of the bore. The annular packing when assembled has an L-shaped cross section with the first leg of said packing adjoining said frontal face and the second leg adjoining said lateral face and said second leg prior to assembly into said fuze cap having a thickness greater than the distance between said lateral face and the Wall of said bore. A melting body is located adjacent the top of said fuze cap and the first leg of the packing is clamped between the melting body and the frontal face. The extension firing pin has a member fastened thereto and the first leg of the packing is clamped between such member and the frontal face. The melting body is provided with grooves.

The invention concerns a percussion fuze for a missile, with a fuze cap, with an extension firing pin having a front surface and a lateral face and which projects movably into a bore of the fuze cap, and whereby the diameter of the lateral face is smaller than the diameter of the bore, with an annular packing which on one side adjoins the front and lateral faces of the extension firing pin and on the other side adjoins the bore wall of the fuze cap.

In a known percussion fuze of this kind the packing is slid over the extension firing pin as a ring with a rectangular or quadrangular cross section and is situated in a relatively narrow space between the lateral wall and the bore wall. It has been found that with a very small fuze cap such as, for example, for the munition of small caliber cannons, this gap has to be constructed in a size range of 0.1 mm. It is however not possible, in a gap of such narrowness, to install a packing ring with a quadrangular cross section as a packing ring of such dimensions cannot be easily produced and would moreover not have the firmness required for assembly.

The aim of the invention is to avoid this disadvantage. The percussion fuze is characterized in that the annular packing shows an L-shaped cross section, in that the first shank is adjacent to the front surface and the second flange to the lateral face, and in that the thickness of the shank adjoining the lateral face is, prior to assembly into the fuze cap. greater than the distance between the lateral face and the bore wall.

The procedure for assembly of the percussion fuze is characterized in that a packing disc is laid upon the front surface of the extension firing pin, is locked by a plate against the front surface, the plate is fastened to the extension firing pin and in that the shank of the packing disc is doubled back during assembly of the extension firing pin and the fuze cap.

3,5 fi,74 8 Patented Mar. 17, 1970 With reference to the attached drawings, three examples of construction of the percussion fuze are described in detail:

FIG. 1 shows a longitudinal section across a percussion fuze according to a first example of construction,

FIG. 2 shows a longitudinal section across the fuze cap of the percussion fuze illustrated in FIG. 1 on an enlarged scale,

FIG. 3 shows a longitudinal section across a percus- S10; fuze according to a second example of construction, an

FIG. 4 shows a longitudinal section across a fuze cap according to a third example of construction.

According to FIG. 1 the percussion fuze has a fuze casing 10, into the back of which is screwed a fuze body 6, having a central bore 9. Behind this central bore 9 is a casing 7, screwed into fuze body 6. Inside this casing 7 there is a detonator charge 3. By means of fuze body 6 a bearing body 11 is clamped inside fuze casing 10. The bearing body 11 has a central bore and a spherical hearing surface 12. A chamber is formed by bearing body 11 and fuze body 6, inside which is housed a rotor 13. This rotor 13 likewise has a central bore 15, inside which there is a primer 14. Before arming of the fuze, the central bore of rotor 13 is inclined opposite the axis of the fuze. Fuze casing 11) has in front a casing-shaped extension 17, which has a bore 18. A percussion casing 19 is arranged on one side inside this bore 18 and on the other side inside the bore of bearing body 11. This percussion casing 19 is charged by a percussion spring 20 placed inside a bore of percussion casing 19 and supporting itself on one side on the bottom of this bore and on the other side on the bottom of bore 18 of the casing-shaped extension 17. In the central bore of percussion casing 19 is arranged a firing pin 21, having a collar 22 and a point 23. With this collar 22 the firing pin 21 supports itself upon rotor 13. The point 23 of firing pin 21 projects into a slot 24 of rotor 13. The plane of symmetry of slot 24 coincides with the plane of the drawing. Under the action of percussion spring 20, percussion casing 19 pushes against collar 22 of firing pin 21, causing firing pin 21 to be pushed with its collar 22 against plane 16 of rotor 13.

Percussion casing 19 has furthermore radial bores 25, inside which there are centrifugal bodies 26 which, under the centrifugal force action of the rotating fuze, support themselves upon a conical plane 27 of bearing body 11 (in drawing only one centrifugal body is shown).

According to FIG. 1, a detonating rod 28 supports itself upon a front surface of firing pin 21. This extension firing pin 28 projects into a central bore of fuze cap 29. This fuze cap 29 is screwed on top of fuze casing 10 of the fuze. As shown in FIG. 2, extension firing pin 28 has a flange-like extension 31 with a front plane 32 having a diameter smaller than the diameter of the crown bore 30. The head of extension firing pin 28, situated in front of this extension 31, is formed by a cylindrical part 33 and a frontally tapering truncated cone 34. This conical part 34 projects into a centre bore 36 which is arranged inside a ceiling 35 closing off fuze cap 29. The head of the firing pin 33, 34 effects the centering of a packing ring 37 lying on the front surface of flange extension 31 and consisting of polyvinylchloride or of a resistant to aging rubber and an annular melting body 39 arranged between packing ring 37 and crown ceiling 35 and consisting of a metal with a melting point at low temperatures.

The diameter of melting body 39 is smaller than the diameter of extension 31 of extension firing pin 28. On its front surface are radially arranged grooves 40 extending across the entire width of melting body 39. These 3 grooves 49 form a volumetric connection between the space 41, lying between the conical part 34 of the extension firing pin and the inside face of melting body 39, and the annular space, bordered by the fuze cap Wall, surrounding melting body 39. Into this annular space 42 run the bores 43 carried through the wall of fuze cap 29.

In the second example of construction shown in FIG. 3, grooves 44 are also arranged on the backside of melting body 39, as distinct from the first example of construction. Furthermore there is arranged between melting body 39 and packing ring 37 a metallic ring 45, also centered by the extension firing pin. If melting body 39 were lying directly upon packing ring 37, its unpressured parts would during pressuring of packing ring 37 intrude into the rear grooves 44 of melting body 39 and narrow their cross section. The purpose of metallic ring 45 is to avoid this.

As distinct from the second example of construction, in the third example of construction according to FIG. 4, the extension 31, packing ring 37, metallic ring 45 and melting body 39 are arranged on a part 47 forming the extenison of firing pin 28 and supporting itself on same. During assembly of the percussion fuze this part 47 is slid from front to back into bore 48 of casing extension 17 which in this instance projects beyond the fuze cap ceiling, so that the shank 38 of packing 37 is doubled back towards the front and is clamped between the wall of said bore 48 and ring 45.

A further advantage obtained by the arrangement as shown in FIG. 4 consists in that a pressure force, e.g. a water pressure, pressing upon the front surface 49 of shank 38 of packing 37, works to cause an additional, radial pressing of shank 38 against the bore wall and thus an incerase of the sealing action of packing 37.

Packing ring 37, when assembled, shows in all examples of construction an L-shaped cross section and the thickness of shank 33 which projects between bore wall 30 and extension 31 of extension firing pin 28 is, prior to assembly, larger than the distance between bore wall 30 and the lateral face of extension 31. Before fuze cap 29 is mounted, packing ring 37 is level, as indicated in a stippled line on FIG. 2. Prior to assembly, packing ring 37 has a uniform thickness and has an exterior diameter which is larger than the diameter of bore 30. When fuze cap 29 is mounted on the fuze, shank 38 of packing ring 37 which projects beyond extension 31 is doubled back towards the rear. Through elastic deformation shank 38 is clamped between bore wall 30 and the lateral face of extension 31, i.e. it is elastically compressed so that it exerts sealing pressures upon these surfaces.

The method of operation of the three examples of construction of the percussion fuze described is as follows:

During transportation and storage of the fuze the packing 37 prevents water from entering the interior of the fuze through the frontally open head .of fuze cap 29. The screw couplings of the fuze which might also form leakage points, viz the connections between casing 7 and fuze body on the one hand and between fuze casing and fuze body 6 and fuze cap 29 on the other hand, are sealed by known means, e.g. on the basis of epoxy resins.

After firing of a spin stabilized missile fitted with the above described fuze, body 39 melts, the liquid metal being ejected. Since, because of this, firing pin 21 and extension firing pin 28 are no longer held immovably, rotor 13 can now rise under action of the centrifugal force until the axis of bore 15 containing the primer 14 coincides with the longitudinal axis .of the fuze. During said positioning movement of rotor 13 the firing pin 21 with extension firing pin 28, and consequently also percussion casing 19, are pushed forward by the effect of centrifugal force upon rotor 13. The force of the rotor overcomes at this time the force of percussion spring 20, the friction force operating upon packing ring 37 and the aerodynamic pressure operating upon the extension firing pin 28.

When collar 22 of firing pin 21 is no longer supported by rotor 13 but is within the range of bore 15, percussion casing 19 is pushed back again by spring 20 until the centrifugal bodies which, by action of the centrigual force are lying against the wall of bore 46, support themselves upon the conical face of bearing body 11. In this position the fuze is armed. Upon collision with the target the backwards moved extension firing pin drives the firing pin 21 against the primer 14. This causes the detonation of the missile explosive charge, not shown in the drawing, to

commence.

We claim:

1. Percussion fuze for a missile comprising a casing, 21 fuze cap having a bore, a firing pin, an extension firing pin coasting with said pin having a frontal face and a lateral face projecting movably into said bore, the diameter of said lateral face being smaller than the diameter of said bore, an annular packing adjoining on one side the frontal and lateral faces of said extension firing pin and adjoining on the other side the wall of said bore, a ring secured to said extension firing pin, a melting body provided with grooves arranged between said ring and the top of said fuze cap, said annular packing when assembled having an L-shaped cross section with a first leg of said packing clamped between said ring and said frontal face and the second leg adjoining said lateral face and said second leg prior to assembly into said fuze cap having a thickness greater than the distance between said lateral face and the wall of said bore.

2. Percussion fuze as set forth in claim 1 wherein said grooves are provided at the rear of the frontal facing of said melting body.

References Cited UNITED STATES PATENTS 1,287,496 12/1918 Stanek 277--2l2 1,447,931 3/1923 Dickens 2772l2 2,191,605 2/1940 Zehnder 2772l2 2,595,750 5/1962 Brandt 102--78 2,887,342 5/1959 Helsel 277-33 FOREIGN PATENTS 670,769 11/1963 Canada.

OTHER REFERENCES TRW, ER6260-4, Nov. 18, 1968, p. 25.

BENJAMIN A. BORCHELT, Primary Examiner T. H. WEBB, Assistant Examiner US. 01. x.R. 277 21.2 

